Process for sizing paper



March 13, 1928.

- T. HANS PROCESS FOR srzma IAPER Filed Feb. 21. 1927 Patented Mar. 13, 1928.

UNITED STATES PATENT OFFICE.-

THOMAS HANS, OF CHICAGO, ILLINOIS, ASSIGNOR T CONTAINER CORPORATION OF AMERICA, OF CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE.

PROCESS FOR SIZING PAPER.

Application filed February 21, 1927. Serial No. 169,857.

This invention relates to a novel and improved process for sizing paper and consists of the matters hereinafter described and more particularly pointed out in the appended claims.

In the manufacture of paper and particularly of heavy liner sheets used in the manufacture of fibre and corrugated board for boxes and the like, the full amount of sizing required in the paper is introduced into and mixed with the fibrous pulp at the beaters and preliminary to the supply of the liquid containing the pulp to the paper machine. It sometimes happens that the amount of sizing'then incorporated with the fluid fibrous pulp is not sufficient to bring the paper sheet when finished up to the standard of sizing'which was required. As this may only be discovered after the paper sheet is finished and at the point where it is being wound into rolls, it will be manifest that many rolls of paper which are undersized will be produced before the fault may be remedied, since the additional amount of size necessary to bring the sizing u to the required standard can only be added at the heaters.

The object of my invention is to produce a process for sizing paper in which a part of the size is applied to the paper in the course of its passage through the paper machine, instead of having all of it applied at the heaters as is now the general practice.

In the preferred method of carrying on my invention, before the paper sheet leaves the last set of pressure rolls and before it goes to the drying rolls, I provide means by which a sizing solution is applied to the surface of the advancing sheet before it comes to the drying rolls. This application of sizingsolution is made by directing first a spray of resin size across the full width of the surface of the sheet and then at a short distance further beyond in the advance of the sheet by applying a spray of alum solution for precipitating the size upon the fibres of the paper.

In order that the surface of the paper may be rendered porous and thus capable of receiving to some appreciable depth the sizing and alum applied to it, I interpose at the oint where the spray devices are lo oate two or more preliminary drier rolls aboutwhich the advancing sheet is passed with the liner surface'outermost to receive the spray. The said surface being wet and porous, takes up and absorbs the solution of resin, which is then set or precipitated upon the fibre of the paper at and adjacent to the surface when the alum solution is later applied.

The advantage of this method of sizing the paper will be manifest to those familiar w th the art. Since part of the sizing is applied just before the paper is passed to the drying rolls, the only paper lost in case a change or increase in the amount of sizing 1s required in order to bring the sized sheet up to the standard prescribed consists of the length of the sheet extending from the point in the machine where the sizing is applied to the point where the sheet is wound into the rolls.

In order to illustrate the improved process, I attach hereto drawings showing in connection with a paper-making machine, apparatus for carrying out said process. In said drawings, Figure 1 is a view in side elevation of the part of a paper-making machine in the neighborhood of and preceding the usual drying rolls. Figure 2 is a perspective, diagrammatic view showing the spraying devices and the rolls with which they are associated.

In the said drawings, 10 indicates the first one of the usual series of drying rolls in the paper-making machine; 11, 12 and 13 indicate the last set of squeezing rolls which precede the set of drying rolls; 14: indicates the endless felt belt passing about said squeeze rolls as the paper-making machine is usually made; and 15 indicates the advancing paper sheet or web which is being made by the machine. Ordinarily the paper sheet would pass'from the squeeze rolls 12 to the squeeze'rolls 11 as indicated by the dotted line 15*.

In carrying on the sizing process of this application, there are interposed between the locations of the squeeze rolls 12 and 11, a set of preliminary drying rolls (in this case three) 16, 17 and 18. The paper sheet 15 is passed about said drying rolls as illustrated,passing from the squeeze rolls 12 up and about the drying roll 16, with its surface 15 exposed; then about the drying roll 17, with the said surface 15 in contact with the said roll 17 and then about the drying roll 18, again with its said surface 15 exposed. From the drying roll 18 the paper sheet or web passes between the last set 11 of the squeeze rolls and goes thence to the regular drying rolls 10 as heretofore.

19 indicates a spray pipe located adjacent to and extending parallel to the roll 16, and 20 indicates a spray pipe similarly placed with reference to the roll The pipe 19 is adapted for spraying a solution of resin size upon the exposed surface 15* of the paper web or sheet as it passes over the roll 16 and the pipe 20 is adapted for spraying a solution of alum of proportionate strength to the said surface 15 as the paper sheet passes about the roll 18.

As said sheet passes about the roll 16, the pores of the exposed surface 15" appear to be somewhat opened up, so that the spray of sizing solution discharged across the Width of the paper sheet surface penetrates below that surface and soaks into the fibre of the sheet at and near the surface. As the sheet passes with its surface 15 in contact with the intermediate drying roll 17, the excess moisture on said surface is removed. Then, when the sheet passes about the roll 18, the fixing, alum solution, discharged as a spray across the surface 15, penetrates the still open pores of the surface and precipitates the size upon the fibres of the sheet to the extent that the sizing solution has penetrated that surface. The excess moisture of the alum solution is then pressed out as the sheet passes through the last set 11 of squeezing rolls. The paper sheet is then dried in the usual manner by passing it through the drying rolls of which 10 represents the first.

The advantages of the new process will be manifest. The strength and quantity of the sizing solution applied by the spray pipes may be easil and quickly modified or changed as desired at any time and the sizing incorporated in the paper may be va'ied as shown to be necessary from examination of a sample of the finished paper at a point but a comparatively short length of paper beyond the point where the final character and amount of the sizing is determined. And this may be done without re ard to the quantity of size incorporated at t e beaters, which may provide a basic invariable factor as to size to be incorporated in any and all paper to be made on a run of the machine.

claim as my inventlon:

1. In the manufacture of paper in' a continuous web, the process of sizin which ineludes the spraying of a sizing so ution upon a surface of the advancing sheet at a point preliminary to its passage to the drying rolls.

2. In the manufacture of paper in a continuous web, the process of sizing which includes the application of a sizing solution to a surface of the advancing sheet at a point where the bulk of the moisture has been substantially squeezed therefrom and preliminary to its passage to the drying rolls.

3. In the manufacture of paper in a continous web, the process of sizing which includes the spraying in succession of first a sizing solution and of then a size precipitating solution upon a surface of the advancing sheet at a point preliminary to its passage to the drying rolls.

4. In the manufacture of paper in a continuous web, the process of sizing which includes the application in succession of first a sizing solution and of then a size precipitating solution to a surface of the advancing sheet at a point where the bulk of the moisture has been substantially squeezed therefrom and preliminary to its passage to the drying rolls.

5. ln the manufacture of paper in a continuous web, the process of sizing which includes the application first of .a spray of sizing solution upon a surface of the advancing sheet and then of a spray of a solution of alum on said surface, both at a point after the bulk of the moisture has been squeezed therefrom and preliminary to the passage of the sheet to the drying rolls,

6. In the manufacture of paper in a continuous web, the process of sizing paper which consists in incorporating but a part of the sizing required with the fluid fibrous pulp supplied to the paper-making machine, and of thereafter at a point prior to the entrance of the paper web to the drying rolls, applying in short succession a spray of siz- 1ng solution and a spray of size precipitating solution.

7. In the manufacture of paper in a continuous web, the process of sizing which includes the spraying of a sizing solution upon a surface of the advancing sheet after the bulk of the moisture has been so ueezed therefrom and as said sheet is passe about a preliminary drying roll, of then passing said sheet with the sprayed surface in contact with another drying roll and of then spraying said surface with a size precipitating solution as it is passed about another preliminary drying roll, all in advance of thizl passage of the sheet to the final drying ro s.

8. In the manufacture of paper in a continuous web, the process of sizing which consists in incorporating in the fibrous pulp for making the sheet but a part of the required sizing material and of then spraying a sizing solution upon a surface of the advancing sheet after the bulk of the moisture has been squeezed therefrom and as said sheet is passed about a preliminary drying roll, then passing said sheet with the sprayed surface in contact with another drying roll and then spraying said surface with a size precipitating solution as it is passed about another preliminary drying roll, all in advance of thiel passage of the sheet to the final drying ro s.

9. In the manufacture of paper in a continuous Web, the process of sizing which consists in incorporating in the fibrous pulp for making the sheet a part of the required sizing material before it goes to the papermaking machine, and in then applying a siz- 10 ing solution, variable as desired to bring the size to a predeterminedstandard, to the surface of the advancing sheet as it passes through the paper-making machine at a point in advance of the entrance of the paper sheet into the drying rolls.

In testimony that I claim the foregoing as my invention, I afiix my signature this 19th day of February, A. D. 1927.

THOMAS HANS. 

